Access continuous form takes 100% cpu

I have a problem with an Access application that we have. It runs fine on our XP PC's but has a problem with a few continuous forms, when run on our Windows Server 2003. We are using Access 2003. I am concentrating on one single form - this happens with several similar forms.

The problem is that the listing (of journeys) uses a query that links the journeys table with the driver and passenger tables. When the form is opened it displays the data from the journey table, but the data from the driver and passenger tables is blank and the server cpu is up around 80 - 100%. If left for a few minutes it will eventually display.
I repeat that this only happens on the 2003 server. In all cases the backend is running on a second server (our main file and domain server).

The tables are not significantly larger than they have been in the past.

I have taken the liberty of attaching a cut down database and backend (no sensitive information).

I would welcome any suggestions as to how this problem can be diagnosed and fixed.

There's nothing really complicated. If I run the query on it's own (even on the server) it returns instantly.

I can't see anything complex that would slow it down (I have attached the db so folks can look at it). And anyway, it works fine on an XP PC so it seems like it could be a server issue. I have re-installed Office on the server but it made no difference.

You can check the indexes on the tables - I think they are just a simple index on the Passenger/Driver ID numbers.

Hi Boag2000
Thanks for the suggestions. I have moved the calculated fields into the query and that seems to have solved the problem.
I still do not understand why (a) the problem only occurs on our server and (b) why similar forms with the same calculated fields work fine.
But life's too short to worry too much about that - it all seems to be working fine now.
Thanks for your help.